Is it compulsory to respect a deviant person who claims to be from the descendants of the Holy Prophet ﷺ (sayyids)?
If that person’s deviance does not reach the limit of blasphemy, then one has to respect him. However, if his deviance does reach the limit of blasphemy, then he should not be respected. It is mentioned in the Quran;
إِنَّهُۥ لَيۡسَ مِنۡ أَهۡلِكَۖ إِنَّهُ ۥ عَمَلٌ غَيۡرُ صَـٰلِحٍ۬ۖ
Indeed he is not a part of your family. Indeed, he is (a man of) bad deeds
[Surah Hud verse 46]
Summarized from Ref: Fatawa Amjadiyya: Vol 4 Page 150
Written by Mufti-e-Azam Hazrat Sadrush-Shariah Muhammad Amjad Ali Azmi رحمة الله عليه.
Translated by Shazad Shafi
Answer from alhaneef.com